# Method for controlling generator frequency by output torque of prime motors

## A technology for outputting torque and prime mover, which is applied to control generators, AC networks with the same frequency from different sources, control systems, etc.

Inactive Publication Date: 2015-05-20
STATE GRID CORP OF CHINA +2
3 Cites 1 Cited by

## AI-Extracted Technical Summary

### Problems solved by technology

[0005] What the present invention aims to solve is that the current primary frequency regulation cannot dynamically track the changes of the power grid, and the secondary frequency regulation depends on ...
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## Abstract

The invention discloses a method for controlling generator frequency by output torque of prime motors. The method comprises the following steps: A, computing numerical values of rated power PGi of all units, setting the power regulation range of each unit, and determining a numerical value of a load regulation effect coefficient KLD of an electric network load; B, computing disturbance quantity deltaPi of each unit; C, computing the unit regulation power KGi of each unit; D, performing PI (proportion integration) calculation on each unit according to a difference value deltaf of the real-time frequency f and the rated power fN of a system to obtain the power regulation amount deltaPGi of each unit, and obtaining a formula (5): (deltaPGi-deltaPi)/KLD=deltaf in consideration of the regulation effect of a power load; E, according to the rotor motion equation of each unit, obtaining the real-tome output torque TMi of the prime motor of each unit by combining with the formula (5) obtained in the step D, and controlling the output frequency of the system by taking the worked out TMi as the input of each unit. The method disclosed by the invention has the advantages that a frequency-modulated control method is simple and reliable; the automation of the frequency modulation of an electric power system can be realized; the frequency change of the system is rapidly tracked; the human cost is reduced, and the reliability of the electric power system is impoved.

Application Domain

Power oscillations reduction/preventionElectric generator control +1

Technology Topic

Electric generatorHuman power +10

## Examples

• Experimental program(1)

### Example Embodiment

[0035] Example: A method for controlling generator frequency using prime mover output torque. Taking IEEE's 3 machines and 9 nodes as a simulation case, the system is required to quickly converge to 50Hz when the system suddenly increases by 50MW at t=1.5s. At the same time, the maximum frequency deviation does not exceed 0.02Hz.
[0036] According to the raw data of the IEEE 3-machine and 9-node model, data such as line parameters, transformer parameters, load parameters and generator parameters are analyzed and calculated.
[0037] Such as figure 1 As shown, the control method of the present invention is implemented through the following steps:
[0038] A: Calculate the rated power P of each unit Gi Set the power adjustment range of each unit, and determine the load adjustment effect coefficient K of the grid load LD The numerical value.
[0039] Under the rated operation of the system, calculate the rated power value P of 3 units respectively G1 , P G2 , P G3 , Set the respective power adjustment ranges of the 3 units; and determine the load adjustment effect coefficient K of the grid load LD The numerical value.
[0040] B: Calculate the disturbance ΔP of each unit i.
[0041] First calculate the real-time output power P of the 3 units separately G1 ', P G2 ', P G3 ';
[0042] Combined with the rated power value P of 3 units G1 , P G2 , P G3 , Calculate the change ΔP of the total output power of the unit.
[0043] ΔP = X i = 1 n P Gi ′ - X i = 1 n P Gi - - - ( 1 )
[0044] Then the rated output power of the 3 units P Gi And the change ΔP of the sum of the output power of the units, respectively, into equation (2) to obtain the disturbance ΔP of the three units 1 , ΔP 2 , ΔP 3.
[0045] ΔP i = P Gi X i = 1 n P Gi X ΔP - - - ( 2 )
[0046] Among them, n is the total number of units, P Gi 'Is the real-time output power of the i-th unit, P Gi Is the rated power of the i-th unit, ΔP i Is the disturbance of the i-th unit.
[0047] C: Calculate the unit adjusted power K of each unit Gi.
[0048] The real-time output power P of 3 units G1 ', P G2 ', P G3 'And the rated frequency f of the system N , Respectively put into equation (3), calculate the unit regulated power K of 3 units G1 , K G2 , K G3.
[0049] K Gi = P Gi ′ f N X K Gi * - - - ( 3 )
[0050] Where K Gi Regulate the unit power value for the i-th unit, K Gi * K Gi The standard unit value of, generally takes 16.7-25; in order to meet the actual output capacity of the unit, K Gi Make a limit,
[0051] K Gi (min)≤K Gi ≤K Gi (max) (4)
[0052] Where K Gi (min) and K Gi (max) are the lower limit and upper limit of the unit regulated power of the i-th unit. When K Gi Less than K Gi (min), take K Gi =K Gi (min); When K Gi Greater than K Gi (max), take K Gi =K Gi (max).
[0053] In this embodiment, K G1 * = 20, K G2 * = 25, K G3 * = 17, K G1 (min) = 0.034, K G1 (max) = 0.051; K G2 (min) = 0.065, K G2 (max)=0.098; K G3 (min) = 0.023, K G3 (max)=0.035.
[0054] D: According to the real-time frequency f and rated frequency f of the system N The difference Δf of each unit is performed on the PI calculation of each unit to obtain the power adjustment ΔP of each unit Gi , Considering the regulation effect of electric load, we get
[0055] (ΔP Gi -ΔP i )÷K LD =Δf (5)
[0056] The real-time frequency f of the system and the rated frequency f N The difference Δf is performed on the three units separately to calculate the power adjustment ΔP of the three units G1 , ΔP G2 , ΔP G3.
[0057] Among them, the proportional operation P is equivalent to the primary frequency modulation of the power system, and the proportional coefficients of the 3 units are respectively taken as K G1 , K G2 , K G3. The integral operation I is equivalent to the second frequency modulation of the power system, and the integral coefficient of all units is 0.01.
[0058] Adjust the power adjustment ΔP of 3 units G1 , ΔP G2 , ΔP G3 And the disturbance ΔP of 3 units 1 , ΔP 2 , ΔP 3 , Respectively bring them into formula (5).
[0059] E: According to the rotor motion equation of each unit, combined with the formula (5) obtained in step D to obtain the real-time output torque T of the prime mover of each unit Mi , Will calculate T Mi As the input of each unit to control the output frequency of the system.
[0060] The rotor motion equation of each unit is as follows:
[0061] 1 ΔT i ( S ) = 1 T Ji S + D i X 1 Δf ( S ) X 1 2 π ΔT i = ΔT Mi - ΔT Ei ΔT Mi = T Mi - T MNi ΔT Ei = P Ei ω i - P ENi ω Ni - - - ( 6 )
[0062] Where T Ji Is the inertial time constant of the i-th unit; D i Is the damping coefficient of the i-th unit; ω i Is the real-time angular velocity of the i-th unit, ω Ni Is the rated angular velocity of the i-th unit; T Mi Real-time output mechanical torque for the prime mover of the i-th unit, T MNi Is the rated output mechanical torque of the prime mover of the i-th unit; P Ei Is the real-time electromagnetic power of the i-th unit, P ENi Is the rated electromagnetic power of the i-th unit; ΔT Ei Is the change of electromagnetic torque of the i-th unit; ΔT Mi Is the change in the mechanical torque of the prime mover of the i-th unit; ΔT i It is the difference between the change in the mechanical torque of the prime mover of the i-th unit and the change in the electromagnetic torque of the i-th unit.
[0063] In accordance with the actual project, ignoring losses such as damping friction, the real-time electromagnetic power P Ei Take the real-time output power P of the i-th unit Gi ', the rated electromagnetic power P of the i-th unit ENi Take the rated output power P of the i-th unit Gi , The prime mover rated output mechanical torque T of the i-th unit MNi Take as the rated output torque of the i-th unit
[0064] Substituting the respective difference Δf of the three units in step D into equation (6), the real-time output mechanical torque T of the prime mover of the three units is calculated M1 , T M2 , T M3. Where T M1 , T M2 , T M3 It is a function of the real-time frequency f of the system.
[0065] The calculated prime movers of the 3 units output mechanical torque T in real time M1 , T M2 , T M3 , Respectively as the input of 3 units to control the real-time frequency f of the system.
[0066] The simulated system output frequency diagram of the present invention, such as figure 2 Shown.

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